Jim's 1982 300 Six Bronco Original Restoration

[StraightSix]

Holy hell guys, it's been a wild last few months with not much progress done on the Bronco.

In March I crashed my motorcycle at 60mph on a turn and had to take a break from any repair work. No injuries (I got lucky), just cuts and bruises. When I started feeling better I replaced all the broken stuff on the bike and added some upgrades.

Then I ended up buying a base trim 2001 Dodge Ram 1500 5.2L 4x4 that used to be a Cal Fire work truck until 2019. It had 267k miles when I purchased it, so it needed a bit of work. I fixed up the interior a bit, added a stereo and replaced speakers, replaced the shocks, jerry-rigged a V10 radiator in place, and did most of the engine gaskets. Upgraded the design-defective intake plenum plate with a thicker aftermarket one, so the engine should be bulletproof as it was actually a rebuild (and probably failed from this issue). Steering box was a reman and it went bad. Dropped $500 on a Red Head gear and an aftermarket column bushing. Grabbed some wheels and tires from a 2004 1500 to replace the original steelies. After that, I took it on a 1400 mile trip to Washington and then a kayak camping trip in the Sierras. I also ripped around some OHV trails in Northern California for good measure. After fixing all the oil leaks, the rear main seal began to leak. Not interested in fixing it, I'll just keep adding oil. Also needs some body work on the roof to seal up the holes where the light bar was.

Overall, solid truck it seems like. As a government worker myself, our trucks get fixed the right way for any minor issue, so I'd bet it's had everything replaced at least once considering all the evidence of off-roading I've found behind the interior panels.

Then I got married, sold my Fiesta ST, and was in the process of buying a house. I was getting prepped to potentially move but I pulled out of the home buying process because I figured out my realtor was manipulating me and I was buying a total wreck of a home.

So here I am, ready to get back to work on the Bronco with a good bit of cash from selling my car.

Since my last update, I have removed EVERYTHING from the undercarriage rear of the catalytic converter. Exhaust, leaf springs, fuel tank, axle... Everything is out. Leaf springs got me stuck for a while since the bushings and bolts were seized. Body mounts were also a pain, and they were totally rusted out. I could punch out some of them from the top with a BFH but I snapped the head off a bolt on one and had to sawzall it from the bottom.

So I figured I should probably finally pressure wash the underside of the truck, but it was immobile at this point in time. I made water channels in my garage out of duct tape and went for it. The duct tape worked pretty good at keeping mud in the boundaries.

I'm finishing up the paint in the rear 1/3 of the undercarriage this weekend and then I've got parts here and on order that need to be installed. I won't be putting on an exhaust, anything fuel related, or brake lines until I've moved forward and painted the middle undercarriage and replaced the tranny with a ZF5 or M5OD. I'm having trouble locating a used one that has already been pulled. It's even harder to find one that uses a mechanical speedometer.

I have this metal piece that sits beween the body and the rear bumper. Is this part only for the poverty-spec bumpers, or do I also need it with a step bumper?

Also, I've been toying with the idea of some light performance/quality of life upgrades in the far future. I think I want to go with a 2bbl carb and electric fuel pump or just fuel injection but I'm wary of CA emissions with both. Not trying to do anything crazy, just want a modest boost in power without killing fuel economy.

Hi Jim!

Here are some thoughts-

if you replace the rear glass, pull the window motor out and replace the plastic balls with steel ball bearings. the balls disintegrate with time and use, eventually resulting in the motor spinning but the glass not moving. Im sorry, I thought I had a better photo, but here is the disassembled motor. The plastic balls go in the corners of the triangle in the white plastic piece and prevent the grey wheel from free spinning inside the white piece. I also packed the whole thing with fresh grease.

on the transmission-

what are your rear end gears? if you have 3.00 or 3.55 gears, you might find that you dont need an OD gear to cruise on the highway. I have 3.55s and no OD gear, I can make 65-70 pretty easily and got good fuel economy while doing it. I dont care to drive mine any faster anyways..

if you just have to have an OD gear, the M50D and zf5 are the ones Id look at. the mazda trans should be easier/cheaper to find and would weigh a good bit less, but is much less stout and doesn't have good granny/off-road gears. as Im sure you have already found, the zf5 transmissions are very expensive. its a tough transmission and has a decent granny gear. in either case, swapping to these transmissions will require you to move the trans cross member and get new driveshafts, and maybe some funny business getting your stock (NP208?) transfer case to fit up. keep in mind that atleast with the zf5 you would need the 4x4 version of the transmission, its different than the 2x4. this is probably true for the mazda trans too, but I dont know. on the zf5, the bellhousing is integral to the tranny and they made versions that will not fit your 300. look out!

if you have 3.00 or 3.55 gears and can live without OD ... I vote for an NP435! They are relatively light, tough as a brick outhouse (went in everything from half tons to dump trucks in their day), you can probably get one for less than $200, it has the best (lowest) granny gears of any transmission available to you, it came in the 82 Bronco from the factory so I assume it will be much easier to retrofit to your vehicle than the longer 5 speeds, it will work with you transfer case and drive shafts... the list of benefits goes on and on, at least to me. This is what I have, with 3.55 gears. I cruise at 65 mph @ 2500 rpm, and before I tore the truck down I was getting 16 mpg highway. after the engine and driveline rebuild Im working on now Im hoping for 18 mpg. to get the low gear final drive of the np435 3.55 gear pairing, you would need to have 4.10 rear gears with a zf5.

**edit - I may have spoken too soon on how easy it would be to swap to an NP435. I googled around a bit and the od trans you have is very different from a packaging standpoint.

sorry about the transmission rant..

on engine upgrades -

I dont know anything about your emissions laws, so sorry if these dont help.

- swap EFI exhaust manifolds in? I would think it is possible to preserve the function of the EGR and keep your emissions equipment working, I think Fuzzface did it on one of his. These should give you a notable improvement in torque and felt power, and it seems unlikely to me that the inspection guy would notice or care.

-run a 2.5" exhaust all the way through the back. Walker makes a 2.5" collector pipe that fits the EFI manifolds. can find the part number if you want it.

-internal work in the head would probably help. port and polish, over size valves, etc. this would be something to consider when you rebuild the engine maybe? i just did mine, took about 15 hours. There is also a new "promaxx" head available over on fordsix. It is a factory style iron casting with more meat in the right places, cnc ported and pre cut for oversize valves. Its pricey, but if you want drop in power this is it.

- going to a 2bbl carb and preserving the emissions functionality seems like a tall order to me. Im running a motorcraft 2bbl and like it, but I dont have to worry about emissions. the 300 never came from the factory this way, so it might be difficult to do..

and finally, will the emissions laws allow you to install a newer engine? if you want a mazda 5 speed anyways, why not find an EFI 300 (87-96) mated to a mazda 5 speed? get the engine, transmission, transfer case, drive shafts and transmission tunnel cover all in one go and do a total driveline swap. this would net you a more powerful, torquier engine, better fuel economy, your tranny swap, and hopefully emissions compliance all in one go.

sorry about rambling on and on, but I read your thread last night and had some ideas!

-John

 

[StraightSix]

Hi Jim!

Here are some thoughts-

if you replace the rear glass, pull the window motor out and replace the plastic balls with steel ball bearings. the balls disintegrate with time and use, eventually resulting in the motor spinning but the glass not moving. Im sorry, I thought I had a better photo, but here is the disassembled motor. The plastic balls go in the corners of the triangle in the white plastic piece and prevent the grey wheel from free spinning inside the white piece. I also packed the whole thing with fresh grease.

on the transmission-

what are your rear end gears? if you have 3.00 or 3.55 gears, you might find that you dont need an OD gear to cruise on the highway. I have 3.55s and no OD gear, I can make 65-70 pretty easily and got good fuel economy while doing it. I dont care to drive mine any faster anyways..

if you just have to have an OD gear, the M50D and zf5 are the ones Id look at. the mazda trans should be easier/cheaper to find and would weigh a good bit less, but is much less stout and doesn't have good granny/off-road gears. as Im sure you have already found, the zf5 transmissions are very expensive. its a tough transmission and has a decent granny gear. in either case, swapping to these transmissions will require you to move the trans cross member and get new driveshafts, and maybe some funny business getting your stock (NP208?) transfer case to fit up. keep in mind that atleast with the zf5 you would need the 4x4 version of the transmission, its different than the 2x4. this is probably true for the mazda trans too, but I dont know. on the zf5, the bellhousing is integral to the tranny and they made versions that will not fit your 300. look out!

if you have 3.00 or 3.55 gears and can live without OD ... I vote for an NP435! They are relatively light, tough as a brick outhouse (went in everything from half tons to dump trucks in their day), you can probably get one for less than $200, it has the best (lowest) granny gears of any transmission available to you, it came in the 82 Bronco from the factory so I assume it will be much easier to retrofit to your vehicle than the longer 5 speeds, it will work with you transfer case and drive shafts... the list of benefits goes on and on, at least to me. This is what I have, with 3.55 gears. I cruise at 65 mph @ 2500 rpm, and before I tore the truck down I was getting 16 mpg highway. after the engine and driveline rebuild Im working on now Im hoping for 18 mpg. to get the low gear final drive of the np435 3.55 gear pairing, you would need to have 4.10 rear gears with a zf5.

**edit - I may have spoken too soon on how easy it would be to swap to an NP435. I googled around a bit and the od trans you have is very different from a packaging standpoint.

sorry about the transmission rant..

on engine upgrades -

I dont know anything about your emissions laws, so sorry if these dont help.

- swap EFI exhaust manifolds in? I would think it is possible to preserve the function of the EGR and keep your emissions equipment working, I think Fuzzface did it on one of his. These should give you a notable improvement in torque and felt power, and it seems unlikely to me that the inspection guy would notice or care.

-run a 2.5" exhaust all the way through the back. Walker makes a 2.5" collector pipe that fits the EFI manifolds. can find the part number if you want it.

-internal work in the head would probably help. port and polish, over size valves, etc. this would be something to consider when you rebuild the engine maybe? i just did mine, took about 15 hours. There is also a new "promaxx" head available over on fordsix. It is a factory style iron casting with more meat in the right places, cnc ported and pre cut for oversize valves. Its pricey, but if you want drop in power this is it.

- going to a 2bbl carb and preserving the emissions functionality seems like a tall order to me. Im running a motorcraft 2bbl and like it, but I dont have to worry about emissions. the 300 never came from the factory this way, so it might be difficult to do..

and finally, will the emissions laws allow you to install a newer engine? if you want a mazda 5 speed anyways, why not find an EFI 300 (87-96) mated to a mazda 5 speed? get the engine, transmission, transfer case, drive shafts and transmission tunnel cover all in one go and do a total driveline swap. this would net you a more powerful, torquier engine, better fuel economy, your tranny swap, and hopefully emissions compliance all in one go.

sorry about rambling on and on, but I read your thread last night and had some ideas!

-John

Where did you get that shiny new tailgate? mine is pretty rough. its probably fixable, but not for cheaper than a new tailgate.

[JimJam300]

Where did you get that shiny new tailgate? mine is pretty rough. its probably fixable, but not for cheaper than a new tailgate.

I grabbed that tailgate off a 1989 in the junkyard. I bolted it to the truck and found that 2 of the mounting threads were stripped and it is mis-aligned. It has all the parts within, but it's in rough shape. It was an impulse buy pretty much.

So my truck has 3.00 gears, a SROD toploader, NP208 case, and 31" tires. I was wary of the bellhousing applications of the ZF5, which has made it much harder to locate one. A local auto parts distributor can get me a rebuilt ZF5 small block 4WD for $2000 + core (and I don't have an eligible core) so I've been scouring the web for anything else. Most of the ones I find are big block, 2WD, and if I get lucky and find a small block 4WD it's for electronic speedo. M5R2s are equally difficult to find, as most of them are 2WD and electronic speedo. Facing this reality on top of having to do a bunch of work once I actually get the trans is pretty demoralizing. I'd like to have a better range of gears but I'd also like a functioning truck (and I'd also like to drop the SROD into a volcano).

So throwing the NP435 into the ring should also warrant consideration of the T18 and T19. I think your suggestion is good considering I have 3.00 diffs. According to the internet which is always reliable their gear ratios are as follows:

This is all I know so far: The T18/19 and NP435 can take the small block bellhousing and NP208 already bolted to my SROD. All three can also use the mechanical clutch and speedo. With the T18/19 I don't need to chop my driveshaft, but I don't know about the NP. The T18 does not have a synchro 1st. Seems like the T19 has almost the same gear ratios as an M5R2 without the 5th overdrive, and the ZF5 has the same 2nd and 3rd as the T18. People online say the NP435 shifts smoother than the T18/T19 which sounds nice. Any one of these in 4th is going to give my 70mph at 2300rpm according to this calculator.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

My SROD has either a 3.01 or 3.25 first gear which requires lots of throttle to get it moving. When I had a Ranger with 3.73 gears and a M5R1 with a 3.91 first gear and same size tires, I could ALMOST get it moving without the throttle, but it struggled when hauling a heavy load. That was with a 4.0 V6 which is rated 220ft-lbs at 2400rpm, whereas a carb'd 300 will hit 223ft-lbs at 1600rpm. So I'm not sure if the Bronco with highway gears and a much sooner peak torque will do much better than my Ranger with a same or similar 1st gear ratio. It'd be nice to have a transmission that's great for towing, but who knows if I'll even be doing that. Maybe I can throw in a NP435 and then do a ZF5 when I have the time and money.

NP435

Pros: Cheap, granny 1st., synchro 1st

Cons: WIDE ratio, 3.34 2nd might be annoying to start out in all the time

T18

Pros: Cheap, granny 1st

Cons: Wide ratio, no synchro 1st, even worse 2nd gear

T19

Pros: Cheap, close ratio

Cons: No granny 1st

ZF5

Pros: Faster granny 1st, overdrive, modern

Cons: expensive, lots of work, wide ratio--might need to re-gear to take full advantage of

M5R2

Pros: Close ratio, overdrive, modern

Cons: lots of work, dubious towing capability

As for the engine, I was planning on getting EFI manifolds and getting them ported. A ported head would be awesome as well. If I'm going to yank the engine and rebuild it I might as well put nicer parts in there. The big issue with the 2bbl carb is passing visual inspection. I might be able to hide it under all stock parts, and the truck is probably old enough that a smog technician might not know what stock even looks like. If I can't do it, then I'll have to figure out some other ways to make more power with that 1bbl. Or I'll have to do some research to find if there's a CARB-legal aftermarket EFI kit because swapping in an EFI motor and harness sounds like a chore.

We're getting to the point where it's hard or impossible to find original emissions-compliant parts on 1980s cars, let alone 1970s cars. I don't get why California thought it was okay to stop rolling forward smog exemptions every year. A 1976 model year vehicle is now 46 years old, try keeping that 100% original and clean-running.

[StraightSix]

I grabbed that tailgate off a 1989 in the junkyard. I bolted it to the truck and found that 2 of the mounting threads were stripped and it is mis-aligned. It has all the parts within, but it's in rough shape. It was an impulse buy pretty much.

So my truck has 3.00 gears, a SROD toploader, NP208 case, and 31" tires. I was wary of the bellhousing applications of the ZF5, which has made it much harder to locate one. A local auto parts distributor can get me a rebuilt ZF5 small block 4WD for $2000 + core (and I don't have an eligible core) so I've been scouring the web for anything else. Most of the ones I find are big block, 2WD, and if I get lucky and find a small block 4WD it's for electronic speedo. M5R2s are equally difficult to find, as most of them are 2WD and electronic speedo. Facing this reality on top of having to do a bunch of work once I actually get the trans is pretty demoralizing. I'd like to have a better range of gears but I'd also like a functioning truck (and I'd also like to drop the SROD into a volcano).

So throwing the NP435 into the ring should also warrant consideration of the T18 and T19. I think your suggestion is good considering I have 3.00 diffs. According to the internet which is always reliable their gear ratios are as follows:

This is all I know so far: The T18/19 and NP435 can take the small block bellhousing and NP208 already bolted to my SROD. All three can also use the mechanical clutch and speedo. With the T18/19 I don't need to chop my driveshaft, but I don't know about the NP. The T18 does not have a synchro 1st. Seems like the T19 has almost the same gear ratios as an M5R2 without the 5th overdrive, and the ZF5 has the same 2nd and 3rd as the T18. People online say the NP435 shifts smoother than the T18/T19 which sounds nice. Any one of these in 4th is going to give my 70mph at 2300rpm according to this calculator.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

My SROD has either a 3.01 or 3.25 first gear which requires lots of throttle to get it moving. When I had a Ranger with 3.73 gears and a M5R1 with a 3.91 first gear and same size tires, I could ALMOST get it moving without the throttle, but it struggled when hauling a heavy load. That was with a 4.0 V6 which is rated 220ft-lbs at 2400rpm, whereas a carb'd 300 will hit 223ft-lbs at 1600rpm. So I'm not sure if the Bronco with highway gears and a much sooner peak torque will do much better than my Ranger with a same or similar 1st gear ratio. It'd be nice to have a transmission that's great for towing, but who knows if I'll even be doing that. Maybe I can throw in a NP435 and then do a ZF5 when I have the time and money.

NP435

Pros: Cheap, granny 1st., synchro 1st

Cons: WIDE ratio, 3.34 2nd might be annoying to start out in all the time

T18

Pros: Cheap, granny 1st

Cons: Wide ratio, no synchro 1st, even worse 2nd gear

T19

Pros: Cheap, close ratio

Cons: No granny 1st

ZF5

Pros: Faster granny 1st, overdrive, modern

Cons: expensive, lots of work, wide ratio--might need to re-gear to take full advantage of

M5R2

Pros: Close ratio, overdrive, modern

Cons: lots of work, dubious towing capability

As for the engine, I was planning on getting EFI manifolds and getting them ported. A ported head would be awesome as well. If I'm going to yank the engine and rebuild it I might as well put nicer parts in there. The big issue with the 2bbl carb is passing visual inspection. I might be able to hide it under all stock parts, and the truck is probably old enough that a smog technician might not know what stock even looks like. If I can't do it, then I'll have to figure out some other ways to make more power with that 1bbl. Or I'll have to do some research to find if there's a CARB-legal aftermarket EFI kit because swapping in an EFI motor and harness sounds like a chore.

We're getting to the point where it's hard or impossible to find original emissions-compliant parts on 1980s cars, let alone 1970s cars. I don't get why California thought it was okay to stop rolling forward smog exemptions every year. A 1976 model year vehicle is now 46 years old, try keeping that 100% original and clean-running.

A few notes-

The np435 does not have a synchronized 1st gear. 1st and reverse are non synchronized. The np435 and the t18/19 are all pretty much identical in size. Anywhere one would fit, I assume the others will too. I would expect the driveshafts to be the same between np435/t18/t19. There is a diesel close rang t19 that you might like, I think granny is about 4:1?

Starting in 2nd is easy with my 3.55s, and I can even pull off a 3rd gear start though its not practical to do so. My buddy has a dodge pickup with an np435, np208, and 3.23 rear gears. It starts and drives well in 2nd. 3.00 (or is it 3.08?) Gears like yours, Ive never tried. Who knows. With a little low end torque boost you might find that starting in 2nd isnt much of an issue. That could always be a carb tuning issue too. Make sure your pump shot is working correctly. New plugs and checking the timing might help too. You probably already did all of that though.

I think thats about going price for a zf5.. $2500

Ill be following along for sure!

[StraightSix]

A few notes-

The np435 does not have a synchronized 1st gear. 1st and reverse are non synchronized. The np435 and the t18/19 are all pretty much identical in size. Anywhere one would fit, I assume the others will too. I would expect the driveshafts to be the same between np435/t18/t19. There is a diesel close rang t19 that you might like, I think granny is about 4:1?

Starting in 2nd is easy with my 3.55s, and I can even pull off a 3rd gear start though its not practical to do so. My buddy has a dodge pickup with an np435, np208, and 3.23 rear gears. It starts and drives well in 2nd. 3.00 (or is it 3.08?) Gears like yours, Ive never tried. Who knows. With a little low end torque boost you might find that starting in 2nd isnt much of an issue. That could always be a carb tuning issue too. Make sure your pump shot is working correctly. New plugs and checking the timing might help too. You probably already did all of that though.

I think thats about going price for a zf5.. $2500

Ill be following along for sure!

here is something I dont understand about your problem. your trucks speedo cable goes to your np208, not your transmission. I guess I just dont know how the electric speedos work, but perhaps you can ignore whatever speedo provisions a transmission has or doesnt have since your speedo is mechanically driven by the transfer case?

thought a little more on your transmission/ gearing issue.

these are transmission/axle/transfer case cumulative gear ratios for your truck with either an np435 or a zf5. This assume 31" tires. a few take aways from this for me- you probably arent really going to want to start in 1st with the zf5, I think its a little too low and you would eventually end up starting in 2nd. additionally, the od gear gets you up to pretty much crazy speeds with your 3.08 gears. by contrast, the np435 2nd gear is a little lower meaning easier starts, and it doesnt have the od gear but I wouldnt personally mind that. It will be much easier to package in your vehicle, any you can get one for less than $200. rebuild kits are $300 or less, if you want it to be fresh. thats only 20% of hte cost to get a zf5 in your hands, plus retrofitting the zf5 may be non trivial.

I know the 435 has wide ratios, but I kinda like it because youre up to speed in 2 gear shifts. Its pretty much a 3 speed. I think the roughly 4.0 1st gears in the t19 and Mazda 5 speed may suit you well if you dont care about having a low granny. I would take the t19 over the mazda because its more stout, easier to get into your truck with less cost and less changes, and in my opinion, the od gear in the mazda gets you moving faster than I would really want to go. also, my 300 is kinda spun out by 4rth, it will cruise happily up hills on the highway as long as I keep it over 1800 rpm or so, but Id imagine that od gear might put your 300 in a place where it doesnt want to pull on the highway. this is all a pretty personal choice, sorry if Im crowding you with my opinions.

[FuzzFace2]

A few notes-

The np435 does not have a synchronized 1st gear. 1st and reverse are non synchronized. The np435 and the t18/19 are all pretty much identical in size. Anywhere one would fit, I assume the others will too. I would expect the driveshafts to be the same between np435/t18/t19. There is a diesel close rang t19 that you might like, I think granny is about 4:1?

I think thats about going price for a zf5.. $2500

Ill be following along for sure!

THat is all true the only trans with synchro first is the T19 of the 3 listed above.

I swapped out a T18 for a NP435 and with all the measure I did it would be a bolt in even the drive shaft.

I said would be as I did an Advance Adapter over drive and that moved the trans back 7.5" so a new drive shaft was needed.

My 81 F100 flare side is a 4x2, has a 300 six, NP435 trans and a 2.75 rear gear and running 235 x 75 x 15 tires. I drive it as a 3 sp starting in 2nd gear as the granny is to low unless pulling a heavy load. Truck was build as a driver and a back up to pull my open deck car trailer.

The 300 will get the job done just not vary fast.

Now with the OD I can split all the gears if I want. Some of the ratios are really to close for everyday driving / splitting but with the large spread between 2nd & 3rd I like to split 2nd when up shifting notso much when down shifting. I have yet to pull my trailer or any heavy load in the bed.

In 4th OD the motor is turning 1800 RPM @ 70 MPH

That is the same RPM @ 55 MPH in direct drive

FYI OD is 2200 RPM @ 80 MPH

Direct is 2800 RPM @ 80 MPH

The speed limit here is 70 MPH and no one dose that!

The OD has not helped the MPG but not spinning the motor high is nice.

Dave ----

[FuzzFace2]

A few notes-

The np435 does not have a synchronized 1st gear. 1st and reverse are non synchronized. The np435 and the t18/19 are all pretty much identical in size. Anywhere one would fit, I assume the others will too. I would expect the driveshafts to be the same between np435/t18/t19. There is a diesel close rang t19 that you might like, I think granny is about 4:1?

I think thats about going price for a zf5.. $2500

Ill be following along for sure!

THat is all true the only trans with synchro first is the T19 of the 3 listed above.

I swapped out a T18 for a NP435 and with all the measure I did it would be a bolt in even the drive shaft.

I said would be as I did an Advance Adapter over drive and that moved the trans back 7.5" so a new drive shaft was needed.

My 81 F100 flare side is a 4x2, has a 300 six, NP435 trans and a 2.75 rear gear and running 235 x 75 x 15 tires. I drive it as a 3 sp starting in 2nd gear as the granny is to low unless pulling a heavy load. Truck was build as a driver and a back up to pull my open deck car trailer.

The 300 will get the job done just not vary fast.

Now with the OD I can split all the gears if I want. Some of the ratios are really to close for everyday driving / splitting but with the large spread between 2nd & 3rd I like to split 2nd when up shifting notso much when down shifting. I have yet to pull my trailer or any heavy load in the bed.

In 4th OD the motor is turning 1800 RPM @ 70 MPH

That is the same RPM @ 55 MPH in direct drive

FYI OD is 2200 RPM @ 80 MPH

Direct is 2800 RPM @ 80 MPH

The speed limit here is 70 MPH and no one dose that!

The OD has not helped the MPG but not spinning the motor high is nice.

Dave ----

Oh I also had the same issues trying to find a ZF or M5R2 trans and why I did the Advance Adapter OD

Dave ----

[Ford F834]

I grabbed that tailgate off a 1989 in the junkyard. I bolted it to the truck and found that 2 of the mounting threads were stripped and it is mis-aligned. It has all the parts within, but it's in rough shape. It was an impulse buy pretty much.

So my truck has 3.00 gears, a SROD toploader, NP208 case, and 31" tires. I was wary of the bellhousing applications of the ZF5, which has made it much harder to locate one. A local auto parts distributor can get me a rebuilt ZF5 small block 4WD for $2000 + core (and I don't have an eligible core) so I've been scouring the web for anything else. Most of the ones I find are big block, 2WD, and if I get lucky and find a small block 4WD it's for electronic speedo. M5R2s are equally difficult to find, as most of them are 2WD and electronic speedo. Facing this reality on top of having to do a bunch of work once I actually get the trans is pretty demoralizing. I'd like to have a better range of gears but I'd also like a functioning truck (and I'd also like to drop the SROD into a volcano).

So throwing the NP435 into the ring should also warrant consideration of the T18 and T19. I think your suggestion is good considering I have 3.00 diffs. According to the internet which is always reliable their gear ratios are as follows:

This is all I know so far: The T18/19 and NP435 can take the small block bellhousing and NP208 already bolted to my SROD. All three can also use the mechanical clutch and speedo. With the T18/19 I don't need to chop my driveshaft, but I don't know about the NP. The T18 does not have a synchro 1st. Seems like the T19 has almost the same gear ratios as an M5R2 without the 5th overdrive, and the ZF5 has the same 2nd and 3rd as the T18. People online say the NP435 shifts smoother than the T18/T19 which sounds nice. Any one of these in 4th is going to give my 70mph at 2300rpm according to this calculator.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

My SROD has either a 3.01 or 3.25 first gear which requires lots of throttle to get it moving. When I had a Ranger with 3.73 gears and a M5R1 with a 3.91 first gear and same size tires, I could ALMOST get it moving without the throttle, but it struggled when hauling a heavy load. That was with a 4.0 V6 which is rated 220ft-lbs at 2400rpm, whereas a carb'd 300 will hit 223ft-lbs at 1600rpm. So I'm not sure if the Bronco with highway gears and a much sooner peak torque will do much better than my Ranger with a same or similar 1st gear ratio. It'd be nice to have a transmission that's great for towing, but who knows if I'll even be doing that. Maybe I can throw in a NP435 and then do a ZF5 when I have the time and money.

NP435

Pros: Cheap, granny 1st., synchro 1st

Cons: WIDE ratio, 3.34 2nd might be annoying to start out in all the time

T18

Pros: Cheap, granny 1st

Cons: Wide ratio, no synchro 1st, even worse 2nd gear

T19

Pros: Cheap, close ratio

Cons: No granny 1st

ZF5

Pros: Faster granny 1st, overdrive, modern

Cons: expensive, lots of work, wide ratio--might need to re-gear to take full advantage of

M5R2

Pros: Close ratio, overdrive, modern

Cons: lots of work, dubious towing capability

As for the engine, I was planning on getting EFI manifolds and getting them ported. A ported head would be awesome as well. If I'm going to yank the engine and rebuild it I might as well put nicer parts in there. The big issue with the 2bbl carb is passing visual inspection. I might be able to hide it under all stock parts, and the truck is probably old enough that a smog technician might not know what stock even looks like. If I can't do it, then I'll have to figure out some other ways to make more power with that 1bbl. Or I'll have to do some research to find if there's a CARB-legal aftermarket EFI kit because swapping in an EFI motor and harness sounds like a chore.

We're getting to the point where it's hard or impossible to find original emissions-compliant parts on 1980s cars, let alone 1970s cars. I don't get why California thought it was okay to stop rolling forward smog exemptions every year. A 1976 model year vehicle is now 46 years old, try keeping that 100% original and clean-running.

Hello, I really like your Bronco and have enjoyed reading about your build.

I just wanted to toss in my .02 on the transmission choice. I converted my 1981 F150 to 4wd. It has a 300 straight six and I have 3.00 axle gears. I’m running 235/85R16’s which are just proud of 31” when new. I chose to use the close ratio T19 out of my F350 diesel. There are three different T19’s, mine is the one with the 4.02 synchronized first gear. Overall I am happy with it, and below are my real world observations (good and bad) after living with this choice for 4 years.

With this axle ratio and tire size I am not really lacking in overdrive gearing. It could stand to be just a touch taller geared on a perfectly flat highway, but as it is, it doesn’t take much of a hill to bog it down. I can hold 4th gear on a long 6% interstate grade, but my speed drops to ~50mph or so. The real beauty of the close ratio T19 is the 3rd gear. If I feel like I’m loosing the battle in 4th I can down shift to 3rd and it is strong and right where I need it (4.23 final drive ratio) not screaming and slowing you down even more like the wide ratio 4 speed gear boxes. This is a huge help with the straight six low torque peak power band. I knew the close ratios would be nice, but I underestimated the magnitude of the benefit.

To touch again on the overdrive, or lack thereof, in 4th the sweet spot seems to be 62-67mph. I’ve run mine as fast as 80mph on the straight away, and it has no problem doing 70-75mph, but mine needs ball joints and the steering shaft and gear box are not as tight as they were 40 years ago so I feel safer keeping my speed down. In the 62-67mph sweet spot I get around 17.5 mpg which is respectable for an old full size 4x4. I still have room to improve with tuning, but I doubt that adding overdrive would help all that much.

The 4.02 start out gear is great for general driving and light hauling. I haul water to my property, and it starts out easily with 2,300+ lb tank in the bed. Our 4,500 lb travel trailer is a bit hard on the clutch, and if I need to start out uphill I use the transfer case low range. If you haul heavy frequently you may prefer something with a lower first.

For back country travel, the close ratio wins again. We spent a week on the back roads of Death Valley, and where wide ratio gear boxes jump from lugging to screaming, the close ratio has nice small steps that keep you wheeling comfortably in both low and high range. Again, I under estimated how helpful this would be. I’m not saying this is the right or perfect gear box for every occasion, but it has served me well and shifts as smooth as any truck transmission I’ve had.

[JimJam300]

Hello, I really like your Bronco and have enjoyed reading about your build.

I just wanted to toss in my .02 on the transmission choice. I converted my 1981 F150 to 4wd. It has a 300 straight six and I have 3.00 axle gears. I’m running 235/85R16’s which are just proud of 31” when new. I chose to use the close ratio T19 out of my F350 diesel. There are three different T19’s, mine is the one with the 4.02 synchronized first gear. Overall I am happy with it, and below are my real world observations (good and bad) after living with this choice for 4 years.

With this axle ratio and tire size I am not really lacking in overdrive gearing. It could stand to be just a touch taller geared on a perfectly flat highway, but as it is, it doesn’t take much of a hill to bog it down. I can hold 4th gear on a long 6% interstate grade, but my speed drops to ~50mph or so. The real beauty of the close ratio T19 is the 3rd gear. If I feel like I’m loosing the battle in 4th I can down shift to 3rd and it is strong and right where I need it (4.23 final drive ratio) not screaming and slowing you down even more like the wide ratio 4 speed gear boxes. This is a huge help with the straight six low torque peak power band. I knew the close ratios would be nice, but I underestimated the magnitude of the benefit.

To touch again on the overdrive, or lack thereof, in 4th the sweet spot seems to be 62-67mph. I’ve run mine as fast as 80mph on the straight away, and it has no problem doing 70-75mph, but mine needs ball joints and the steering shaft and gear box are not as tight as they were 40 years ago so I feel safer keeping my speed down. In the 62-67mph sweet spot I get around 17.5 mpg which is respectable for an old full size 4x4. I still have room to improve with tuning, but I doubt that adding overdrive would help all that much.

The 4.02 start out gear is great for general driving and light hauling. I haul water to my property, and it starts out easily with 2,300+ lb tank in the bed. Our 4,500 lb travel trailer is a bit hard on the clutch, and if I need to start out uphill I use the transfer case low range. If you haul heavy frequently you may prefer something with a lower first.

For back country travel, the close ratio wins again. We spent a week on the back roads of Death Valley, and where wide ratio gear boxes jump from lugging to screaming, the close ratio has nice small steps that keep you wheeling comfortably in both low and high range. Again, I under estimated how helpful this would be. I’m not saying this is the right or perfect gear box for every occasion, but it has served me well and shifts as smooth as any truck transmission I’ve had.

Over the past few days I've been thinking pretty hard about this.

I think I'm with you on not needing overdrive. I'm so used to the last manual I owned that I can barely remember what it feels like to drive and shift an old truck.

I don't even own anything that I can tow (yet), and this truck is going to be too nice for off-roading, so having a granny gear is not a necessity. Having those close ratios seems a lot nicer for everyday driving and the car I just sold was a 6spd so I'm already used to constantly shifting.

So I've been scouring the web for a T-19 and info. I found a 4x4 version at a junkyard for $155 which is too cheap to pass up, but I don't know which version it is. There's also a 2WD I found that's in great shape and it is FOR SURE a T-19A with the 4.02:1 1st gear. I figured I could use the shop at work to rebuild at least one of them since we have hoists, a hydraulic press, gearbox tools, parts washers, etc. So my understanding of converting a 2WD trans to a 4WD is swapping over the main shaft and xfer case adapter, which of course, is easier said than done. I've never opened up a transmission before but I asked an ex-mechanic co-worker about rebuilding old 4 speed manuals and he said it shouldn't be out of my reach.

The only thing I'm not sure about is what adapter I need for my NP208 case. Will a NP203 adapter work? Or can I use the one on the back of my SROD?

[StraightSix]

Over the past few days I've been thinking pretty hard about this.

I think I'm with you on not needing overdrive. I'm so used to the last manual I owned that I can barely remember what it feels like to drive and shift an old truck.

I don't even own anything that I can tow (yet), and this truck is going to be too nice for off-roading, so having a granny gear is not a necessity. Having those close ratios seems a lot nicer for everyday driving and the car I just sold was a 6spd so I'm already used to constantly shifting.

So I've been scouring the web for a T-19 and info. I found a 4x4 version at a junkyard for $155 which is too cheap to pass up, but I don't know which version it is. There's also a 2WD I found that's in great shape and it is FOR SURE a T-19A with the 4.02:1 1st gear. I figured I could use the shop at work to rebuild at least one of them since we have hoists, a hydraulic press, gearbox tools, parts washers, etc. So my understanding of converting a 2WD trans to a 4WD is swapping over the main shaft and xfer case adapter, which of course, is easier said than done. I've never opened up a transmission before but I asked an ex-mechanic co-worker about rebuilding old 4 speed manuals and he said it shouldn't be out of my reach.

The only thing I'm not sure about is what adapter I need for my NP208 case. Will a NP203 adapter work? Or can I use the one on the back of my SROD?

Glad you have some direction!

id just buy the 4x4 version. $155 is a smokin good deal. to test the input/output ratio for 1st, just put it in first and spin the input. count revs on input and output. you might have to make some paint marker marks to get precise enough, but should be easy. at least in "np435 land" the bolt pattern on the back of the transfer case for the 4wd adapter is different than the 2wd yoke set up, so at least in "np435 land" it would not be possible to put a transfer case on the back of a 2wd np435 with a factory adapter. also, the replacement shaft you would need may cost more than that whole $155 t19.

as for what adapter you would need to find to put your 208 on the back of a t19, I assume the t18/19/np435 - to - np208 adapters are all the same. mine is np435 to np208. Ill measure the bolt pattern on the back of my transmission and get the numbers to you. it its the same as the back of the t19, Id think it safe to assume they are universal. perhaps make a tracing of your 208 flange and take it with you to the yard, and maybe they have an adapter sitting around too. they have the transmission, after all. keep in mind that youll also need the "stuff" to get your transfer case shift lever on the driver side of the transmission. This will include the transmission tunnel cover.

you rebuilt an axle, right? if so, Id say rebuilding a t19 should be very achievable for you. I havent done a t19, but I helped a friend with an np435 last year and Im half way through rebuilding mine now. I assume the t19 isnt much more complex. I bought a rebuild kit from Novak. I think you can find comparable kits for a little less, but theirs ships with a very well written instruction booklet, step by step, in order with pictures. Its a good compliment to the factory manual.

perhaps post good photos of your srod adapter? we can compare it to mine, which is sitting on my work bench now. my adapter has a cast in boss on the driver side that constitutes the pivot point for the transfer case shift lever, Im sure youll need that.

I think there is a good chance FuzzFace already knows the answers to some of your questions.